Protective end cap construction

ABSTRACT

Protective single- and double-end caps which fit into the ends of a hollow paper core about which sheet material is wound and having splines which accommodate variations in core diameter and toothlike projections superimposed on the splines to provide a barblike holding action.

i te I l l l I Inventor Walter G. Vogell 1827 lhlalght Ave, BronxCounty, NY. 10461 Appl. No. 9,829

Filed Felt. 9, 11970 Patented lDec. M, 11971] Assignee loly Guard, Inc.

Yonkers, NY.

Continuation-impart of application Ser. No. 817,875, Apr. 21, 1969, nowabandoned. This application Feb. 9, 1970, Ser. No. 9,829

PROTECTIVE END CAlP CONSTRUCTION 14 Claims, 11 Drawing Figs.

US. Cl 242/606, 206/59 R, 206/65 R lint. Cl 365d 85/67, B65l1 19/00llField of Search 206/59 R,

[56] References Cited UNITED STATES PATENTS 2,424,553 7/1947 COllti206/52 2,868,602 1/1959 0161661... 287/2 3,004,784 10/1961 Selby 287/23,260,362 7/1966 Schwinne 206/59R 3,335,858 8/1967 Sibille 206/65YFOREIGN PATENTS 769,574 10/1967 Canada 242/68.6 888,860 2/1962GreatBritain 206/59R Primary Examiner-William T. Dixson, Jr. Atmrney-Brooks, Haidt & Haffner' ABSTRACT: Protective singleand double-end capswhich fit into the ends of a hollow paper core about which sheetmaterial is wound and having splines whiclh accommodate variations incore diameter and toothlike projections superimposed on the splines toprovide a barblike holding action PROTECTIVE END CAP CONSTRUCTHGN Thisis a continuation-in-part of copending application Ser. No. 817,875filed Apr. 2 l, 1969 now abandoned.

This invention relates to end caps for protecting the ends of hollowpaper cores and more particularly it concerns novel arrangements whichenable inexpensively manufactured end caps to be maintained securely inplace when pushed into the ends of paper cores.

End caps, otherwise known as core plugs, are used to protest the ends ofhollow paper cores about which plastic or other sheet material is woundfor storage or shipment. The end caps, which are usually made of metalor plastic, comprise a cylindrical plug portion which fits closely intothe ends of the paper cores, and an outwardly extending external flangeportion about the outer edge of the cylindrical portion which covers andprotects the end of the core.

Both end caps and the cores which they protect must be capable of beingproduced very inexpensively since they are essentially disposable items.The cores are usually made of heavy paper or paperboard in tubular form;and the end caps are either drawn from sheet metal or molded fromplastic.

One of the most common difficulties encountered with end caps and coresof previous construction is that of maintaining the end caps tightly inplace during shipment. Often, the end caps would fall out without beingnoticed. Then when the core is set down or dropped, its unprotected endis damaged; and in many cases the material wound about the core is alsodamaged.

It has been difficult to provide end caps which would always stay inplace in the cores because the cores, being made of paper, cannot beheld to a close internal diameter tolerance. Thus, while an end cap mayfit tightly into one core, it will slip out of another. One techniqueemployed in the past to overcome this situation has been to provideaxially extending ribs or splines on the outer surface of the bodyportion of the end cap which inserts into the paper core. These splinesare of sufficient height to fit tightly even into the largest corediameter; and in the case of smaller core diameters the core will deformor partially flatten between the splines, thus allowing them to entertightly into the core. This technique, however, is not entirelysatisfactory for it depends upon the resiliency of the core, that is,its tendency to return to rounded condition which is relied upon tomaintain sufficient pressure against the splines to hold the end captightly in place. In actual practice, the core simply loses itsresiliency and eventually the end cap slips out of place.

Another technique employed to ensure that end caps will remain securelyin place in the ends of hollow cores is to form toothlike projectionsabout the outer surface of the body portion of the end cap. Theseprojections are designed to dig into the inner surface of the paper corein the manner ofa barb and hold the end cap in place. This arrangementis not altogether satisfactory for in many cases the projections willsimply cut longitudinal grooves into the paper core and will not,therefore, be capable of booking into the material of the core. Anotherdifficulty with the toothed projection arrangement is that separateoperations are required to form the projections; and this addsconsiderably to the cost of the finished product.

The present invention overcomes these above-described difficulties ofthe prior art.

According to the present invention, there is provided a novel end capconstruction formed of injection molded plastic material having acylindrical body portion and an outwardly extending flangelikeprojection at one end thereof. A plurality of axially extending ribs areformed about the body portion and a series of small toothlikeprojections are formed along the upper surface of the ribs.

A novel cooperation is achieved between the ribs and the toothlikeprojections in the end cap of the present invention. The toothlikeprojections are made quite small, i.e., less than the height of theribs. This permits them to be formed in a simple injection moldingdevice without need for special operations or special operations whichthe severe undercuts of large toothlike formations would require. Inaddition, the ribs themselves permit a close fit between the end cap anda paper core; and the small teeth on top of the ribs may be forced intothe core to provide barblike holding action without the cutting ofgrooves which larger teeth produce.

According to a further aspect of the present invention there is provideda novel double-end cap construction for use between adjacent axiallyaligned cores. This novel double-end cap construction is speciallyarranged to pennit fabrication in a single simple injection moldingoperation. The novel doubleend cap of the present invention involves apair of coaxially arranged cylindrical walls held in position by meansof axially and radially extending ribs, and an outer flange extendingabout the outer surface of the outer cylindrical wall midway along itslength. This arrangement permits molding dies to operate in an axialdirection from opposite ends to produce a complete integral structure inone operation. Moreover, this arrangement permits the incorporation of acentral flange wall extending from the inner to the outer cylindricalwalls, for strengthening purposes, at a location substantially coplanarwith the outer flange.

Various further and more specific objects, features and advantages ofthe invention will appear from the description given below, taken inconnection with the accompanying drawings, illustrating by way ofexample preferred forms of the invention.

In the drawings:

FIG. I1 is a perspective view illustrating a fully loaded paper coreinto which an end cap according to the present invention is inserted;

FIG. 2 is an enlarged exploded view illustrating one end of the hollowpaper core of FIG. I and end cap associated therewith;

FIG. 3 is an enlarged end view of the end cap shown in FIG.

FIG. 4 is an opposite end view of the end cap shown in FIG.

FIG. 5 is an enlarged section view taken along line 5-5 of FIG. 3;

FIG. 6 is an enlarged fragmentary portion of the end cap shown in FIG. 5inserted into the paper core;

FIG. 7 is a further enlarged fragmentary view illustrating theinteraction between a toothlike projection on the end cap of FIG. 6 andthe corresponding region of the hollow paper core;

FIG. h is an enlarged fragmentary section view taken along line 8-8 ofFIG. 6.

FIG. 9 is an exploded view of a multiple core and double end capassembly forming another embodiment of the present invention;

FIG. 10 is an enlarged end view of the double-end cap of FIG. 9; and

FIG. Ill is a section view taken along line llI-- ill of FIG. 10.

As shown in FIG. I, an elongated hollow paper core 10 has wound thereonan elongated sheet or film 12, of paper, plastic or other material to bepackaged for shipment or storage. An injection molded plastic end cap 14is provided at each end of the core I'll. These end caps serve toprotect the core 10 and the material 112 during storage or shipment.Thus, the end caps 1141 act to absorb initial impact shocks whenever thecore is dropped on one end.

In addition, the plastic end caps are provided with a central opening16, through which a mounting shaft may be extended for mounting theentire assembly while the sheet material 12 is being withdrawntherefrom.

Turning now to FIG. 2, it will be seen that the end cap 14 comprises acylindrical body portion 1% and a flange portion 20, which extendsoutwardly from one end of the cylindrical body portion 18. An innercylindrical wall 22, defining the central opening 116, is arrangedcoaxially within the cylindrical body portion 18, and is supportedtherein by means of a plurality of radially extending vanes 24.

A plurality of axially extending external splines 26 are formed on theouter surface of the body portion 18, and a series of small toothlikeprojections 28 are formed along the upper surface of the splines 26. Ascan be seen in FIG. 2, the plastic end cap 14is configured such that itsbody portion 18, including the splines 26 and the toothlike projections28, can be inserted into the interior of the hollow paper core from theend thereof. In this arrangement, the flange portion of the plastic endcap 14 abuts the end of the paper core 10. As can be seen in FIG. 2, thesplines 26 are arranged in alignment with the vanes 24. The advantagesresulting from this arrangement will be discussed more fullyhereinafter.

Turning now to FIG. 3, it will be seen that the vanes 24 are exposed atthe flange end of the end cap 14. These vanes extend from the end of theinner cylindrical wall 22, which is within the cylindrical body portion18, to the beginning of the flange portion 20. As shown in FIG. 4, thereis provided an annular wall 30 which covers the opposite end of thevanes 24, and which extends between the cylindrical body portion 18 andthe inner cylindrical wall 22. As shown in FIG. 5, one end of the innercylindrical wall 22 is coplanar with the corresponding end of thecylindrical body portion I8 and the annular wall 30. The vanes 24, asstated above, merge witltthe outer end of the cylindrical body portion18 precisely where it meets the flange portion 20. Actually, thecylindrical body portion 18 and the flange portion 20 are joined by aradius 32; and it is at an intermediate region of this radius that thevanes 24 join with the cylindrical body portion 18. It will beappreciated that with this arrangement the vanes 24, in addition tosupporting the inner cylindrical wall 22 with respect to the cylindricalbody portion 18, further serve to reinforce the flange portion 20,thereby enabling it to withstand the shocks and stresses which occurwhen a mallet is used to drive the end cap 14 into the core 10, or whenthe core 10 is dropped on one end.

As shown in FIG. 5, the cylindrical body portion 18 is slightly taperedso that it may wedge into the hollow paper core 10. In addition, thesplines 26 follow the slight taper of the cylindrical body portion 18.Each spline 26 is provided with three of the toothlike projections 28.These projections are displaced axially along each spline and are alsodimensioned to follow the general taper of the spline and body portion.i

As can be seen in FIG. 5, an interference fit is provided between thesplines 26 and the hollow paper core 10. The core, however, canaccommodate this interference fit by flattening somewhat in the regionsbetween the splines 26 and the hollow paper core 10, will depend uponthe particular internal diameter of the paper core. This may vary fromcore to core because of the relatively loose manufacturing tolerancesassociated with such items; or it may change from time to time for anindividual core due to the shrinkage and expansion characteristics ofthe paper from which the core is made. It is important that the plasticend cap 14 be securely maintained in place in spite of these corediameter variations.

Turning now to FIG. 6, it will be seen that when the plastic end cap 14is fully in place, the splines 26 force outwardly on the inner surfaceof the hollow paper core 10 thereby providing a wedging action whichhelps to hold the end cap in place. As shown in FIGS. 6, 7 and 8, thetoothlike projections 28, which extend upwardly from the tops of thesplines 26, individually penetrate further into the surface of thehollow paper core 10. The projections 28 are generally teardropped inshape and have a definite upper, though rounded, corner 29. In addition,the projections 28 are considerably smaller in height than the splines26. This permits the projections to push upwardly and outwardly atconcentrated locations within the hollow paper core but at the same timeit prevents them from forming permanent longitudinal gouges or channelsalong the inner surface of the core when the end cap 14 is forced intoplace. Thus. as can be seen in FIGS. 6 and 7, the material of the papercore is merely pushed aside by the projections 28, and thereaftersettles back around behind each of the individual projections 28 toprovide surfaces against which the projections may perform a barblikeholding action to prevent the end cap from slipping out from the core.

It will be appreciated from the above that the toothlike projections 28cooperate with the splines 26 in that the splines serve to accommodatethe diameter variation encountered in the paper core 10, while the smalltoothlike projections 28 operate to hold the end cap securely in placeby penetrating into the hollow paper core at displaced locations.Moreover, because the toothlike projections 28 are not required toaccommodate core diameter variations (this being handled by the splineson which the projections are superimposed), the projections 28 can bemade large enough to provide a barblike holding action without at thesame time being so large as to cause gouging of the core which woulddefeat the barb action.

The plastic end cap 14, as indicated above, is made of injection moldedplastic. The use of this material in conjunction with the particulardesign of the splines 26 and the toothlike projections 28, permits arapid and very economical method of manufacture. It is known thatinjection molded plastics possess a certain memory" characteristic bywhich they may be molded in a die which is undercut to a certain extent;and when they are retracted from the die they will squeeze in so as topermit such retraction and thereafter they will assume the shape whichthey possessed when they were being formed in the die itself. Thus, solong as the undercuts to be formed (i.e., those which form the toothlikeprojections 28), are not too severe it is possible to form theseprojections or undercuts in a simple die structure without the need forspecial composite multiple action die arrangements. Of course, sinceprojections of this nature involve undercuts, they could not be formedon drawn metal objects without separate forming operations.

By way of example, an end cap for protecting hollow cores having anominal 3-inch inner diameter has an outer body portion diameter whichtapers inwardly at an angle of about 2 from a maximum diameter of 3.030inches to a minimum diameter of 2.980 inches. This end cap has eightequally spaced splines approximately 0.017 inches in height. Thetoothlike projections themselves extend 0.005 to 0.0 l0 inches above thesplines. The outer surface contours of the projections are rounded andfree of sharp corners.

Also as indicated previously, the splines 26 are arranged in alignmentwith the vanes 24. This arrangement ensures that the end cap will bemost solidly reinforced radially at those locations where the splines 26and the toothlike projections 28 engage the hollow paper core 10. Thus,any deformation which occurs will take place in the core 10 and not inthe end cap 14. A further feature of the cooperative arrangement betweenthe vanes 24 and the splines 26 lies in the fact that the plasticmaterial is concentrated most heavily in the region of the toothlikeprojections 28. This concentration of plastic material results in aslower cooling of the material following the injection molding process.Because the material cools more slowly in this region, the toothlikeprojections 28 are not fully hardened at the time the end cap 14 isremoved from the injection molding die in which it is formed. Thus, theprojections 28 are less likely to be sheared off and form sharp cornersas the end cap 14 is removed from the die. Instead, the toothlikeprojections merely deform to a certain degree during removal andthereafter they reassume their initial configuration.

FIGS. 9-ll show another embodiment of the present invention which isused for the packaging of several core rolls in stacked or alignedarrangement.

As seen in FIG. 9 there is provided a double-end cap 40 which extendsinto and forms a connection between two axially aligned cores 42 onwhich rolls 44 of sheet material are wound. The cores 42 are of the sameconstruction as the core 10 of FIG. 1.

The overall configuration of the double-end cap 40 resembles two of thesingle-end caps 14 glued together back to back. The present constructionhowever avoids the necessity of separate fabrication and assembly ofdifferent elements. Instead, with the present construction a double-endcap suitable for interconnecting two axially aligned cores may becompletely fabricated in a single molding operation.

The construction of the double-end cap tltl is best seen in FIGS. litand 111. As there shown the double end cap comprises inner and outercylindrical walls as and d@ maintained in coaxial alignment by means ofa central annular flange wall 50 and a plurality of axially and radiallyextending ribs 52. The inner wall l7 has a central opening 53therethrough which may accommodate an axle or other supporting shaft(not shown). The annular flan ge wall 50 is positioned approximatelyhalf way along the axial length of the inner and outer cylin" dricalwalls as and th. The ribs 52 extend radially from the inner cylindricalwall as to the outer cylindrical wall th, and axially from the oppositesides of the annular flange wall 50.

It will be noted that the radial ribs 32 on one side of the annular wallMl are staggered with respect to the ribs 52 on the opposite side of thewall $0. This arrangement has been found to provide better flow ofplastic material during the molding operation than is obtained where theribs on the opposite sides of the wall ate aligned. The staggered ribarrangement also avoids the buildup of a large concentrated mass ofplastic in one region. Such a large concentration of plastic isundesirable in the molding operation since the plastic material in suchregions would cool more slowly than the adjacent plastic material andthus may give rise to dimensional distortion of the finished product.

An outer flange 54! extends around the outside of the outer cylindricalwall 1% approximately midway along its length. As shown in FIG. ill, theouter flange 5 1i is located in generally coplanar relationship with theflange wall 50.

The outer cylindrical wall Ml is tapered slightly on opposite sides ofthe outer flange 54, and axially extending splines ss are distributedabout the outer surface of the wall 48. Preferably. for purposes ofstrength, these splines are aligned with the corresponding ribs 52.

The double-end cap 4H) is used as shown in FIG. 9. The portions of theouter cylindrical wall as on opposite sides of the outer flange 54extend respectively into the ends of two adjacent cores t2 therebyholding them in alignment. The diameter of the outer cylindrical wall asand the height of the splines 56 are chosen to ensure a snug fit intoeach core. It is not usually necessary however to provide special meansto prevent slipping out of the double-end cap $0 for it will be held inplace by the adjacent rolls M themselves. Thus in such instances theprotrusions described in connection with the preceding embodiments maybe dispensed with.

It will be appreciated that the particular construction of thedouble-end cap 50 makes possible complete fabrication by injectionmolding of plastic in a single operation. The mold dies may approachfrom opposite directions to form the radially and axially extending ribs52 and the portions of the inner and outer cylindrical walls l6 and $8on opposite sides of the annular flange wall 50 and the outer flange 54.There are no undercuts, reverse bends or overhangs which would requirecomplex or multiple die operations. The entire forming operation is thuscompleted in one action and none of the assembly or other complexfabrication procedures such as are required in prior art arrangementsare needed with the present construction.

it will be appreciated that the end cap configurations of the presentinvention ensure a secure and reliable fit with hollow paper cores whichare subject to internal diameter variations. At the same time, the endcaps of the present invention are easily and economically manufactured.

What is claimed is:

I. An end cap for protecting hollow paper cores comprising a hollowcylindrical molded plastic body portion having an outwardly extendingexternal flange portion about one edge thereof, a plurality of axiallyextending circumferentially displaced splines distributed about andextending along the outer surface of said body portion and a pluralityof toothlike projections superimposed upon said splines, said toothlikeprojections having definite, though rounded, upper corners and being ofless height than the splines on which they are superimposed.

2. An end cap according to claim ll wherein said body portion has aslight taper and wherein said splines and toothlike projections followsaid taper.

3. An end cap according to claim ll wherein said toothlike projectionsare free of sharp corners.

4. An end cap according to claim ll wherein said toothlike projectionsare of teardrop configuration.

5. An end cap according to claim ll wherein the height of the toothlikeprojections is related to the plastic material of which they are formedsuch that they may be withdrawn from an undercut mold without beingsheared by the mold upon withdrawal therefrom.

6. An end cap according to claim ll'wherein said body portion is formedwith a plurality of radially extending internal reinforcing vanes whichterminate at an inner surface of said body portion in alignment withsaid splines.

7. An end cap according to claim ll wherein said flange and bodyportions are joined by a curved connecting region and wherein said bodyportion includes radially extending internal reinforcing vanes whichterminate at an inner surface of said body portion and extend along saidinner surface to a location along said curved connecting region.

8. in combination a hollow tubular core of paperlilce material and atleast one plastic end cap forced into an end of said core, said end caphaving a hollow cylindrical body portion and axially extending splinesdistributed thereabout and forming an interference fit at displacedlocations about said core and a plurality of toothlike projectionssuperimposed on said splines and penetrating into the inner surface ofsaid core, said toothlilte projections having definite, though rounded,upper corners and being of less height than the splines on which theyare superimposed.

9. A combination according to claim 8 wherein the inner surface of saidpaper core surrounds each toothlike projection and is free of gouges inthe region of said projections.

110. A double-end cap for protecting hollow paper cores comprising anintegral unitary molded plastic structure having a pair of coaxiallyarranged cylindrical inner and outer walls separated by a plurality ofradially and axially extending ribs and an outer flange extending outfrom and around the outer cylindrical wall midway along the lengththereof.

1111. A double-end cap according to claim Ml and further including acentral flange wall extending from the inner to the outer cylindricalwall, midway along the length thereof.

12. A double-end cap according to claim 10 and further inciuding aplurality of axially extending splines distributed about the outersurface of said outer cylindrical wall on both sides of said outerflange.

l3. A double-end cap according to claim 11 wherein the ribs on one sideof said central flange wall are rotationally offset and thereby mutuallystaggered with respect to the ribs on the opposite side of said centralflange wall.

Ml. A double-end cap according to claim l2 wherein said splines arealigned with said ribs.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORECTION Patent No. 3,27,220 Dated December 14. 1971 ln en fl Walter G. Voqel It iscertified'that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, lines 44-45, after "condition", insert It is this tendency toreturn to rounded condition Column 3, line 46, before "splines", insertadjacent lines 46-47, after "splines 26", insert The degree ofinterference between the splines 26 Signed and sealed this 17th day 0-5October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PC4050 (10459) USCOMM-DC wave-Poo U.S. GOVERNMENTPRINTNG OFFICE I959 DS6G"3$,

1. An end cap for protecting hollow paper cores comprising a hollowcylindrical molded plastic body portion having an outwardly extendingexternal flange portion about one edge thereof, a plurality of axiallyextending circumferentially displaced splines distributed about andextending along the outer surface of said body portion and a pluralityof toothlike projections superimposed upon said splines, said toothlikeprojections having definite, though rounded, upper corners and being ofless height than the splines on which they are superimposed.
 2. An endcap according to claim 1 wherein said body portion has a slight taperand wherein said splines and toothlike projections follow said taper. 3.An end cap according to claim 1 wherein said toothlike projections arefree of sharp corners.
 4. An end cap according to claim 1 wherein saidtoothlike projections are of teardrop configuration.
 5. An end capaccording to claim 1 wherein the height of the toothlike projections isrelated to the plastic material of which they are formed such that theymay be withdrawn from an undercut mold without being sheared by the moldupon withdrawal therefrom.
 6. An end cap according to claim 1 whereinsaid body portion is formed with a plurality of radially extendinginternal reinforcing vanes which terminate at an inner surface of saidbody portion in alignment with said splines.
 7. An end cap according toclaim 1 wherein said flange and body portions are joined by a curvedconnecting region and wherein said body portion includes radiallyextending internal reinforcing vanes which terminate at an inner surfaceof said body portion and extend along said inner surface to a locationalong said curved connecting region.
 8. In combination a hollow tubularcore of paperlike material and at least one plastic end cap forced intoan end of said core, said end cap having a hollow cylindrical bodyportion and axially extending splines distributed thereabout and formingan interference fit at displaced locations about said core and aplurality of toothlike projections superimposed on said splines andpenetrating into the inner surface of said core, said toothlikeprojections having definite, though rounded, upper corners and being ofless height than the splines on which they are superimposed.
 9. Acombination according to claim 8 wherein the inner surface of said papercore surrounds each toothlike projection and is free of gouges in theregion of said projections.
 10. A double-end cap for protecting hollowpaper cores comprising an integral unitary mOlded plastic structurehaving a pair of coaxially arranged cylindrical inner and outer wallsseparated by a plurality of radially and axially extending ribs and anouter flange extending out from and around the outer cylindrical wallmidway along the length thereof.
 11. A double-end cap according to claim10 and further including a central flange wall extending from the innerto the outer cylindrical wall, midway along the length thereof.
 12. Adouble-end cap according to claim 10 and further including a pluralityof axially extending splines distributed about the outer surface of saidouter cylindrical wall on both sides of said outer flange.
 13. Adouble-end cap according to claim 11 wherein the ribs on one side ofsaid central flange wall are rotationally offset and thereby mutuallystaggered with respect to the ribs on the opposite side of said centralflange wall.
 14. A double-end cap according to claim 12 wherein saidsplines are aligned with said ribs.